FM Transmitter - THZY Black Wireless FM Transmitter with 3.5mm Audio Plug and Car Charger for iPhone 6/5/4, iPad, iPod, Samsung Devices, and Any Smart Phones with 3.5mm Audio Plug Play audio devices and smartphones through your car stereo system with 3.5 mm jack. Comes with an extra USB port to charge your cell phones, GPS and other digital devices while driving. Features a high-contrast, easily-read display and prominent button controls. Simply plug in your audio device through 3.5mm jack, set a ramdon FM channel, and tune the car FM audio to that channel. Package includes: 1x THZY FM Transmitter;1x User Manual. First please make sure you find empty stations(pure statics) in your area. You can find the empty stations manually or you can use websites(Radio-Locator and SiriusXM) for help. Simply type in your zip code or location, and these sites show you which stations are the best to use for your transmitter. Second, make sure the volume is proper. The volume at around 3/4 seems to work best with FM transmitters.